Drilling fluid

ABSTRACT

An aqueous drilling fluid dispersant and a method of drilling wells using said drilling fluid which contains as the dispersant a dihydroxyalkanone.

Uniied States Patent inventor Charles M. lilarbordl Bryan, Tex. Appl. No. 887,719 Filed Dec. 23, 1969 Patented Nov. 16, 1971 Assignee Texaco Inc.

New York, N.Y.

DRILLING FLUID 8 Claims, No Drawings US. Cl 252/8.5 C, 252/351 Hm. Cl ..C10m 3/116, ClOm 3/14 Field of Search 252/8.5 C,

Primary Examiner-Herbert B. Guynn AnomeysThomas H. Whaley, Carl G. Ries and James F.

Young ABSTRACT: An aqueous drilling fluid dispersant and a method of drilling wells using said drilling fluid which contains as the dispersant a dihydroxyalkanone.

DRILLING FLUID This invention relates to a novel aqueous drilling fluid for drilling wells through subsurface formations by means of welldrilling tools, and particularly to such an aqueous well-drilling fluid having improved dispersibility as a result of containing therein a novel dispersant as hereinafter more fully described. The invention is also concerned with a method of drilling wells employing the novel aqueous drilling fluid.

Drilling fluids, or muds as they are sometimes called, are slurries of clayey solids used in the drilling of wells for tapping underground collections of oil, gas, brine or water. Such fluids have a number of different functions, the most important of which are to assist in the removal of cuttings from the well, to seal off formations of gas, oil or water which may be encountered at different levels, to lubricate the drilling tool and drill pipe which carries the tool, and to hold the cuttings in suspension in event of shutdowns in drilling.

An ideal drilling fluid is a thixotropic colloidal system, i.e., a fluid which on agitation or circulation (as by pumping or otherwise), has a measurable relatively low viscosity and is free flowing (not plastic), particularly at high temperatures; but when such agitation or circulation is halted, the fluid sets or gels. The rate of gel formation is such as to permit the cuttings to fall only a short distance before the gel structure is sufficiently strong to support them.

When such drilling fluid having the proper viscosity, the proper gel rate and proper gel strength is circulated through a well bore, it has a sufficiently high viscosity to carry the cuttings and sand from the bottom of the hole to the surface and it has a gel rate such as to allow the cuttings and sand to settle in a settling pit. On standing in a quiescent state, it develops sufiicient gel strength to prevent the settling of the cuttings, sand or weighting material, etc., in the well bore when it becomes necessary to discontinue circulation for any appreciable period of time. Such a fluid is also characterized by its ability to form a mudcake on the borehole wall, thereby assisting in sealing off the traversed formations and inhibiting so-called water loss, i.e., loss of water from the drilling fluid.

One of the principal problems in mud chemistry is the production of suitable drilling fluids having satisfactory dispersibility, and the necessary thixotropic properties discussed above.

In accordance with the present invention the problems of dispersibility in aqueous drilling fluids can be solved by incorporating in an aqueous drilling fluid as the dispersant a dihydroxydialkanone in an amount sufficient to reduce the viscosity thereof. Representative ketones include 1,3- dihydroxypropanone, 1,3, dihydroxy-Z-butanone and 1,4- dihydroxy-Z-butanone.

It is known from the article appearing in Zhur. Priklad. Khim. 35, pp. 638-647 (1962), Organic Viscosity Reducers in Clay Solutions" by D. Tischenko and S. Fleisher (CA, 57 2491 g, 1962), that the ortho-dihydroxybenzenesulfonic acids, the ortho-dihydroxy-alpha-toluenesulfonic acids and orthodihydrxy-alpha-toluenesulfonic acids and water-soluble salts thereof are viscosity-reducing agents in clay-laden drilling fluids whereas the corresponding metaand para-dihydroxybenzenes including the corresponding sulfonic acid derivatives and water-soluble salts thereof are ineffective viscosityreducing agents for aqueous drilling fluids.

The dihydroxyalkanones of the present invention may be added to an aqueous drilling fluid in amounts ranging from about 0.1 pound to about pounds per barrel of drilling fluid. In general, it has been found that amounts less than 0.1 pound per barrel do not produce completely satisfactory results in terms of dispersing activity whereas amounts above about 10 pounds per barrel are economically unattractive and no improved results are obtained therewith. A preferred range for the l,3-dihydroxyalkanones of the present invention is from about I to about 3 pounds per barrel of drilling fluid for most consistent results and efficiency.

In the table, gel strength (Gels) is reported as determined by u shcuromctcr in accordance with the procedure in the American Petroleum Institute publication RP-29, results being expressed either as pounds/ square feet or as time in seconds for a tube to settle in the mud (after the mud as stood for zero time and for 10 minutes). If it settles in more than 60 seconds, shear is reported as pounds per 100 square feet. Yield Point (Y?) is calculated by subtracting the Plastic Viscosity (PV) from the Fann Viscosity reading at 300 r.p.m. Plastic Viscosity (PV) is obtained by calculation, subtracting the Fann Reading at 300 r.p.m. from the 600 r.p.m. reading. Apparent Viscosity (AV) is equal to one'half of the Fann Viscosity reading obtained at 600 r.p.m. The fluidity of a mud can be back calculated from these data, the results being expressed in Fann Viscosity at 600 r.p.m. and 300 r.p.m. for a directreading viscosimeter.

The properties of the base mud are shown in the table.

The test data set forth in the following table indicates the effectiveness of the nov l dispersant in improving the dispersibility of drilling fluids.

Representative physical properties of drilling fluids both before and after addition of the novel dihydroxyalkanones of the present invention are shown in the table. In each example the amount of material or materials added to the base muds, if any, are shown, expressed in terms of pounds of material per barrel of drilling fluid.

1,3-dlhydr0xy-2-propanone.

The data in the above table examples la and lb show that the 1,3-dihydroxy-2-proponone is a good drilling fluid dispersant in aqueous low pH systems as demonstrated by the relatively low Yield Point and Gel Strength values obtained therewith.

I claim:

1. An aqueous drilling fluid containing clay solids and as the dispersant a dihydroxyalkanone selected! from the group consisting of 1,3-dihydroxypropanone, 1,3, dlihydroxy-Z-butanone and 1,4-dihydroxy-2-butanone in an amount sufficient to impart a reduced viscosity thereto.

2. An aqueous drilling fluid as claimed in claim 1 wherein the dihydroxyalkanone is 1,3-dihydroxypropanone.

3. An aqueous drilling fluid as claimed in claim 1 wherein the dihydroxyalkanone is l,4-dihydroxy-2-butanone.

4. An aqueous drilling fluid as claimed in claim 1 wherein the dihydroxyalkanone is present in the drilling fluid in an amount of from about 0.1 to about 10 pounds per barrel of drilling fluid.

5. An aqueous drilling fluid as claimed in claim 2 wherein the l,3-dihydroxypropanone is present in the drilling fluid in an amount of from about 1 to about 3 pounds per barrel of drilling fluid.

6. In a method of drilling wells wherein a drilling fluid is passed through the well in contact with earth formations, during the drilling operation, the improvement which comprises contacting said earth formations with an aqueous drilling fluid containing at least 0.] pound per barrel of drilling fluid of 1,3- dihydroxypropanone, said 1,3-dihydroxypropanone being present in the drilling fluid in an amount sufficient to impart a reduced viscosity thereto.

7. In a method of drilling wells as claimed in claim 6 wherein 1,3dihydroxypropanone is present in the drilling fluid in an amount of from 0.1 to 10 pounds per barrel of drilling fluid.

8. In a method of drilling wells as claimed in claim 6 wherein 1,3-dihydroxypropanone is present in the drilling fluid in an amount of from about 1 to about 3 pounds per barrel of drilling fluid. 

2. An aqueous drilling fluid as claimed in claim 1 wherein the dihydroxyalkanone is 1,3-dihydroxypropanone.
 3. An aqueous drilling fluid as claimed in claim 1 wherein the dihydroxyalkanone is 1,4-dihydroxy-2-butanone.
 4. An aqueous drilling fluid as claimed in claim 1 wherein the dihydroxyalkanone is present in the drilling fluid in an amount of from about 0.1 to about 10 pounds per barrel of drilling fluid.
 5. An aqueous drilling fluid as claimed in claim 2 wherein the 1,3-dihydroxypropanone is present in the drilling fluid in an amount of from about 1 to about 3 pounds per barrel of drilling fluid.
 6. In a method of drilling wells wherein a drilling fluid is passed through the well in contact with earth formations, during the drilling operation, the improvement which comprises contacting said earth formations with aN aqueous drilling fluid containing at least 0.1 pound per barrel of drilling fluid of 1, 3-dihydroxypropanone, said 1,3-dihydroxypropanone being present in the drilling fluid in an amount sufficient to impart a reduced viscosity thereto.
 7. In a method of drilling wells as claimed in claim 6 wherein 1,3-dihydroxypropanone is present in the drilling fluid in an amount of from 0.1 to 10 pounds per barrel of drilling fluid.
 8. In a method of drilling wells as claimed in claim 6 wherein 1,3-dihydroxypropanone is present in the drilling fluid in an amount of from about 1 to about 3 pounds per barrel of drilling fluid. 